Printing telegraph manual exchange system



Nov. 16, 1937. E. M. s. MCWHIRTER ET AL 2,099,130

PRINTING TELEGRAPH MANUAL EXCHANGE SYSTEM Filed Oct. 25, 1930 5114.5. M WH/RTE/P J. G. FL/N //V VENTORS ting purposes.

Patented Nov. 16, 1937 UNITED STATES PATENT OFFICE PRINTING TELEGRAPH MANUAL EXCHANGE SYSTEM Eric Malcolm Swift McWhirter and James New York Application October 25, 1930,'Serial No. 491,114 In Great Britain November 6, 1929 18 Claims.

This invention relates to an exchange system for the interconnection of subscriber telegraph apparatus.

According to one feature of the invention the signals for setting up the connection and for the telegraph message after the connection has been set up are sent from a substation over the same circuit.

According to another feature of the invention each substation is connected to the exchange by two wires only which form a complete metallic circuit for the signals for setting up the connection and for telegraphic communication to and from the substation.

According to still another feature of the invention the operators at the exchange are provided with printing telegraph apparatus and each cord circuit contains means for connecting thereto this apparatus so that any communications between subscriber and operator are carried out solely by means of type printing telegraph apparatus.

According to yet another feature of the invention the apparatus at a called station is automatically set in operation to receive a communication on the completion of a connection thereto.

The invention also provides a novel junction circuit which comprises two junction lines only and relays at each end of the junction line connected to repeat telegraph signals in the respective directions and s arranged as to remain unafiected by messages in the opposite direction.

One embodiment of the invention will now be described in connection with the accompanying drawing in which:

Fig. 1 represents the apparatus at a subscribers station and the apparatus associated with his line at the exchange;

Fig. 2 shows an operators cord circuit;

Fig. 3 shows a junction circuit for the interconnection of two telegraphic exchanges; and

Fig. 4 shows a cord circuit by means of which any subscriber may be connected to a plurality of other subscribers.

A type printing telegraph apparatus located at a subscribers station comprises transmitter contacts TC, which when operated by a keyboard or automatic transmitter will open and close a line circuit in accordance with the signals which are to be sent. These contacts are normally closed. The apparatus also comprises printing mechanism controlled by a relay PM responding to the received impulses and a motor 'I'M which drives the mechanism both for printing and transmit- A relay RM of the slow-release type is connected in series with the transmitter contacts and relay PM. The motor is adapted to be connected to the lines PI, P2 of a local source of electric lighting or power supply over the normally open contacts of the relay RM. Contacts TMC are arranged to be closed whenever the motor is running. The subscribers lines Ll, L2, leading to the exchange are closed at the substation through the slow-release relay RM, receiving relay PM, the normally closed transmitter contacts TC, a condenser K, and a pair of polarized relays PRI and PR2. The polarized relays are arranged to operate simultaneously on a battery reversal through the condenser K and will remain in the position to which they were last operated.

In order to initiate a call, the subscriber momentarily depresses a non-locking key CK which closes the circuit of the motor TM which immediately closes its contacts TMC. A calling relay CR at the exchange and the relay RM thereupon operate in a circuit from the positive pole of battery U, contacts of jack CJ, line LI, relay RM, relay PM, contacts TC, normally closed contacts of relay PRI, key RK, contacts TMC, line L2, contacts of jack AJ, relay CR, contacts of jack CJ, negative pole of battery. Relay CR operates, lights a calling lamp CL and a pilot lamp PL and rings an alarm bell AB.

The operator inserts her answering plug AP into the jack AJ and throws the key CCK to the left. This connects her type printing telegraph apparatus OM in series with that at the subscribers station and with the battery U, the circuit being as follows: positive pole of battery U, contacts of jack CJ, line Ll, relay RM, relay PM, contacts TC, contacts of relay PRI, key RK, contacts TMC, line L2, ring spring of jack AJ, ring of plug AP, contacts of key CCK, operators machine OM, back contact of relay CSR, contacts of key CCK, tip of plug AP, tip spring of jack AJ, and negative terminal of battery U. The operator then by typing asks the subscriber for the wanted number which is thereupon typed back to her.

Local call Assume first that the wanted subscriber is on the same exchange. The operator inserts a plug CP of the cord circuit into the jack CJ belonging to the wanted subscriber. The sleeve of the jack CJ is grounded which serves a purpose to be mentioned later and also operates the relay CSR. The battery connected to the springs of the jack CJ of the called subscriber is disconnected and all battery supply is then derived from the battery U connected to the line Ll of the calling subscriber. The condenser K of the called subscriber is charged by the battery U of the calling subscriber; the connection being as follows: positive battery U of ,callingsubscribers line Li, calling subscribers set, line L2, ring of jack AJ and of plug AP, key CCK, contacts of relay CSR, ring of plug CP and of called subscribers jack CJ, line L2; through the called.

subscribers set which includes condenser K, line Ll, tip of jack CJ and of plug CP, contacts of,

relay CSR, tip or" plug AP; and of calling subscribers jack AJ, and negative battery U. Batteries U are preferably separate batteries and they may have in series the usual current limiting resistances. The operatorthenthrows the key CCK to the right and thereby reversesritheconnections between the tips and rings of the plugs AP and CP. The key CCK in this position con nects the tip or plug'AP to thering of plug CP, and the ring of plug AP to the tip of plug CP. .A charging current of short duration flows from battery U of the calling subscriber to .condenser K of the called subscriber, the charge on the condenser K being opposite in polarity to that impressed upon the condenser in the circuit previously traced justbefore the key CCK was thrown to the right. The charging current is suihcient to operate the relays PRI and'PR2 ofv the called subscribers .set. Relay PR2 closes the circuit of the subscribers motor which cominencesito rotate. Relays PR! and PR2 together with the condenser K typify means which operate as a result of current reversals to start the subscribers motor or perform an equivalent function and then remove themselves-from operative relation to the line so that their impedance is no longer effective in thelinel The operator then restores the key CCKtonormal and relays and PR2 restore. The sequence of events The connection between calling and called subscribers is thus complete andcommunication may take place. A message may be, sent by the calling subscriber and receivedon the calledsubscribers instrument in the absence of any operator at the substation. I

The operator at the exchange may connect her own machineOM in series in the circuit bymoving the key CCK to the left, thecircuit then being positive pole of battery U, contacts of jack CJ,

line Li, calling subscribers apparatus; line L2, ring spring of jack AJ, ring'of, plug AP, contacts of key CCK, operators machine OM, contacts of keyCCK, operated contactsof relay CSR, ring of plug CPgcalled subscribersapparatus, tip of plug CR, contacts of key CCK,; operated contacts of'CSR, (two sets), contacts ofkey CCK, tip of plug AP, tip spring of jack AJ, contacts of jack CJ, negative battery. Thus the operator is able to satisfy herself that a satisfactory connection has been completed. t

When the key CCK is restoredtonormal, relay SR is included in the line circuit between the two subscribers. This relay is made slow to release so that the normal telegraphimpulses do not cause it to de-energize.

The release of the connection is under control of the calling subscriber and in orderto release he presses the key RK. This key breaks the short circuit which had been maintained round the relays PRI and PR2 and condenser K and causes the relays RM at each station to de energize. This key RK is held downuntil the contacts of relay RM open after a predetermined time and so stop the motor whereby the contacts TMC 1 open. It may then be assumed that the motor operator inserts the plug CP into the jack OJ belonging to the junction circuit shown in Fig. 3. .Two telegraph relays are provided at each end of a junction circuit. Relays A and C have each two win-dings denoted by Al and A2 and Cl and C2, respectively.l These relays are polarized and their armatures are biased toward the spacing contacts; The relays B and D are telegraph receiving relays. Normally, when the junction circuit is idle, relay A is operated in a 'circuitextending from the negative terminal cit-the local battery G over the operating winding 'Al, back contact of relay B; back contact of relay M, back contacts of relay R, another back contact of relay M, resistance and positive battery G. Relay C is operated in a similar circuit from battery H. The junction lines JLII and JLZ are normally connected in series over the windings of B and D, the holding windings A2 and C2 and marking contacts of relaysA and C. 1

When the operator inserts the calling plug 0? into; the jack OJ, relay M operatesto ground over the spring of the jack OJ and disconnects the above circuit for winding Al, but at its upper front contact relay M switches the battery U (Fig. 1) through to relay A to maintain'the winding Al of-the latter in a circuit from negative battery U (Fig. 1) upper spring of jack CJ, tip of jack AJ, tip of plug AP, uppermost left made contact of key CCK, resistance, front contact of relay CSR, uppermost right contact of key CCK, tip of plugCP, tip of jack OJ, upper front contact of relay M, winding 'Ai, back contact of relay B, ring of jack OJ, ring of plug CP, inner right madecontact of key CCK, front contact of relay CSR, inner left made contact of key CCK, ring oi 'plug AP, ringof jack AJ, line L2 to line Ll, ringof jack CJ to positive battery U. 7

Upon the key CCK (Fig. 2) being thrown to the right the current in-the winding Al is reversed v and causes the armature of relay A to move over to its spacing contact. The armature in this position closes the circuit through the operating winding of relay D at the other end of the junction line in series with the holding Winding C2 of relay C and battery S at the outgoing end of the junction line. The complete circuit extends from the negative terminal of battery S, through armatures of relays :E and A, junction line JLl, armature of relay C, winding C2 of relay C, winding of relay D, and line JLZ to positive terminal of S. The current in the holding windingCZ of relay C aids that in the operating winding and keeps the armature on its marking contact whenthe. relay D is operated. During the time of movement of the armature of relay D,

the winding Cl is disconnected. but a current in the winding C2 prevents any operation of the associated armature. Relay F is then energized in series with the winding Cl and operates a relay CR to light the calling lamp. The operator at the second exchange inserts her plug AP into the jack IJ at the other end of the junction circuit and this causes the operation of relays Q and N to local contacts on the jack, Q being slightly slower to operate than N. Relay N disconnects the winding Cl from the local circuit and reconnects it in the following circuit: tip spring of jack IJ on the right of the figure, lower contact of relay Q, battery EB, upper contact of relay Q make contact of relay N, winding Cl, break contact of relay D, back to the ring spring of the jack IJ. This circuit is at the moment open at the relay D, but as soon as the operator at the first exchange restores the key CCK to normal, relay A operates to its marking contact and the windings C2 and D are deenergized. The armature of relay D is released. During the movement of relay D there is a short time when both windings Cl and C2 are de-energized, but relay F is made slightly slow to release so that any movement of relay C will be without effect at the left-hand end of the junction circuit. As soon as relay D has released, the winding Cl is energized in the circuit previously traced. When relay N operates, the circuits for relays F and CR are broken and the calling lamp extinguished. The operator at the second exchange can now type to the operator at the first exchange, transmission from the second to the first exchange being relayed by relays C and B and transmission from the first exchange to the second exchange being relayed by relays A and D. The calling subscriber is in series in the circuit with the machine of the operator at the first exchange and so can follow the progress of the call.

The operator at the second exchange upon ascertaining the requirements of the call inserts her plug CP into the jack of the wanted subscriber. The connections and operation are similar to a local call on this exchange except that ,the telegraph relays C and D take the place of the calling subscribers machine in the circuit and the necessary signaling current is supplied by the battery EB instead of by the battery U in Fig. 1. When the keys CCK of both operators cord circuits are restored to normal the two subscribers are in communication, but either operator can monitor on the circuit so long as her key CCK is kept to the left.

The release of the connection takes place in a manner similar to that on a local call, the relays THR in each cord circuit operating to light their respective supervisory lamps.

If a subscriber wishes to send a message simultaneously to a plurality of other subscribers, the apparatus shown in Fig. 4 is utilized. The subscriber originates the call in the normal manner and the operator plugs into jack AJ (Fig. 1) with a plug AP (Fig. 2) in the usual way. When the requirements of a subscriber have been ascertained, the operator inserts the plug CP into the jack BJ l in Fig. 4 which connects the tip and ring of the plug CF to a telegraph relay TR. The tongue and marking contacts of this relay are connected through a battery and resistance to the tip and ring springs of a second jack BJ2 into which the operator can insert a plug APB. The plugs CPI to CP4 are inserted into the calling jacks of the required subscribers or. into the jacks of junction circuits if the subscribers are on another exchange. Sleeve relays SRI to SR4 complete the circuits to these plugs only when they have been inserted into a jack. Pressure of the key BCK reverses the connections to all the subscribers lines and thus starts the motors at all the called stations into operation. The calling subscriber can then transmit to all the called subscribers circuits in parallel.

In many cases it will be necessary in order to ensure satisfactory transmission that the batteries U, EB, etc., providing the signaling current should be of a voltage considerably in excess of that used for telephone exchange working and it will be observed that in all cases the sleeves of the jacks, contacts of which are connected to these signaling batteries are grounded, so that the sleeve of the plug is also grounded and the operator effectively protected against shocks.

What is claimed is:

1. In a motor controlling arrangement, a motor, a line connected to a distant source of current, means including a source of power and a circuit changing device responsive to a flow of current in said line for starting said motor, a condenser for obstructing current in said line, and remote control means for short-circuiting said condenser.

2. A motor control arrangement comprising a relay adapted to control a motor circuit, a line connecting said relay to a distant source of current, a condenser and a polarized relay in said line whereby current in the line is obstructed, remote control means for operating said polarized relay, said means comprising a device for reversing the polarity of the distant current source, means responsive to the operation of the polarized relay for starting the motor, and means responsive to the starting of the motor for shortcircuiting said polarized relay and condenser.

3. In a printing telegraph system, a telegraph set comprising a transmitter, a receiver and a motor, a line circuit including said transmitter and receiver in series, a condenser in said series circuit for obstructing current therein when the set is not in use, and means controlled by said motor for automatically short-circuiting said condenser during operation of said motor.

4. In a printing telegraph system, a telegraph set comprising a receiving instrument and a motor, a line circuit including said receiving instrument, and means for starting said motor by remote control, said means comprising a polarized relay and a condenser serially connected in said line circuit, said polarized relay being adapted to close a pair of contacts for the motor circuit upon the receipt from the line of two current impulses of opposite polarity.

5. In a telegraph system, a plurality of subscribers stations each connected to a loop circuit and equipped with a telegraph set for sending and receiving telegraph messages over said loop circuit, means for applying a direct current source to said loop circuit, switching means each of the subscribers stations for switching in and out the subscribers telegraph set to be controlled by a current flow from said direct current source, and a condenser in series with said switching means for preventing a permanent current flow during the time in which the station is not in use.

6. In a telegraph system, a plurality of subscribers stations each connected to a loop circuit and equipped with a telegraph set for sending and receiving telegraph messages over said loop circuit, means for applying a direct current'source to said loop circuit, switching means at each of the subscribers stations for switching in and out the subscribers telegraph set to be controlled by a current flow from said direct current source,

a condenser in series with. said switching means for preventing a permanent current flow during.

the time in which the station is not in use, and other switching means at each of the subscribers stations for short-circuiting the condenser when the station is to be used.

'7. In a telegraph system, a plurality of subscribers stations each connected to a loop circuit and equipped with a telegraph set for sending and receiving telegraph messages over said loop circuit, means for applying a direct current source to said loop circuit, switching means at each of the subscribers stations forswitching in and out the subscribers telegraph set to be controlled by a current flow from said direct current source,

a condenser in series with saidswitching means for preventing a permanent current fiow during the time in which the station is not in use, and other switching means at each of thesubs'cribers? stations for short-circuiting the condenser when the station is to be used, said other switching means being controlled by a device which is operated only when the telegraph set is ready for use.

8. In a telegraph system, a plurality of subscribers stations each connected to a loop circuit and equipped with a telegraph set for sending and receiving telegraph messages over said loop circuit, means for applying a direct current source to said loop circuit, switching means at each of the subscribers stations for switching in and out the subscribers telegraph set to be controlled by a current flow from said direct current source,

a condenser in series with said switching means for preventing a permanent current flow during the time in which the station is not in use, and other switching means at each of the subscribers stations for short-circuiting the condenser when the station is to be used, said other switching means being controlled by a device which is supplied frorn thepower source of the telegraph set.

9. In a telegraph exchange system, an ex-.

change, a plurality of subscribers stations each connected to said exchange over a loop circuit and equipped with a telegraph set for sending and receiving telegraph messages over said loop circuit, means at the exchange for applying a direct current source tosaidloop circuit, switching means at each of the subscribers stations for switching in and out the subscribers telegraph set to be controlled by a current flow from said direct current source, and a condenser in series with said switching means for preventing a permanent current flow during the time in which the station is not in use.

10. In a telegraph exchange system, an exchange, a plurality of subscribers stations each connected to said exchange over a loop circuit and equipped with a telegraph set for sending and receiving telegraph messages over said loop circuit, means at the exchange for applying a direct current source to said loop circuit, switching means at each of the subscribers stations for switching in and out the subscribers telegraph set to be controlled by a current flow from said direct current source, a condenser in series with said switching means for preventing a permanent current flow during the time in which the station is not in use, and otherv switching means at each of the subscribers stations for short-circuiting said condenser when the station is to be used.

11. In a telegraph exchange system, an exchange, a plurality of subscribers stations each connected to said exchange over a loop circuit and equipped with a telegraph set for sending and receiving telegraph messages over said loop cir cuit, means at the exchange for applying a direct current source to said loop circuit, switching means at each of the subscribers stations for switching in and out the subscribers telegraph set to be controlled by a current flow from said direct current source, a condenser in series with said switching means for preventing a permanent current flow during the time in whichthe station'is' not inuse, and, other switching means at each of the subscribers stations for shortcircuiting said condenser when the station is to be used, said other switching means being controlledby a device which is operated only when the telegraph set is ready for use.

12. In a telegraph exchange system, an'cxchange, a plurality of subscribers stations each connected to said exchange over a loop circuit and equipped with a telegraph set for sending and receiving telegraph messages over said loop circuit, means at the exchange for applying a direct current'source to said loop circuit, switching means at each of the subscribers stations for switching in and out the subscribers telegraph set to be controlled by a current flow from said direct current source, a condenser in series with said switching means for preventing a permanent current flow during the time in which the station is not in use, and other switching means at each of the subscribers stations for short-circuiting said condenser when the station is to be used, said other switching means being controlled by a device which is supplied from the power source of the telegraph set.

13. In a telegraph exchange system, an exchange, a plurality of subscribers stations each connected to said exchange over a loop circuit and equipped with a telegraph set for sending and receiving telegraph messages over said loop circuit, means at the exchange for applying opposite direct current potentials to said lcop'circuit, polarized switching means at each of the subscribers stations for switching in and out the Y subscribers telegraph set which are controlled by said direct current potentials, and a condenser in series with said polarized switching means.

14. A printing telegraph subscribers staticnwhich comprises av printing mechanism, a motor for driving said mechanism, motor control means i for controlling said motor, a printing magnet for controlling said printing mechanism, a centrifugally operated contact associated with said driving motor, and a circuit including said prin magnet and centrifugally operated contacts extending to 'a central oflice.

15. A printing telegraph subscribers station comprising a motor driven telegraph printer, a printer magnet associated therewith, a loop circuit including said printer magnet which extends to a central office, and centrifugal means associated with'said motor for maintaining said loop circuit closed as long as said motor is rotating.

16. In a telegraph system, a plurality of sub scribers stations each connected to a' loop circuit and equipped with a telegraph set for sending and receiving telegraph messages over said loop cir cuit, a central office through which said loop circuits, may be interconnected, means for applying a direct current source atsaid central. office to said loop circuit, switching means at each of the subscribers stations for switching in and out the subscribers telegraph set to be controlled by a current flow from said direct current source, a condenser in series with said switching means for preventing a permanent current flow over said loop circuit during the time in which the station is not in use, and other switching means at each of the subscribers stations for removing the condenser from series relation to the loop circuits when the station is to be used.

17. A printing telegraph exchange system comprising a first station, a second station, a line normally open to continuous direct current connecting said stations, a relay connected in said line at said second station responsive to potential reversals applied to said line at said first station for closing said line to direct current, and

additional means whereby the potential reversals applied to said line close the operating circuit for the motor of a printing telegraph instrument located at said second station.

18. A printing telegraph exchange system comprising a first station, a second station, a line normally open to continuous direct current connecting said stations, a relay connected in said line at said second station responsive to potential reversals applied to said line at said first station for closing said line to direct current, and additional apparatus whereby the potential reversals applied to said line start the motor of a printing telegraph instrument located at said second station and also disconnect said relay from operative relation to said line.

ERIC MALCOLM SWIFT MCWHIR'IER. JAMES GEORGE FLINT. 

